1. Field of the Invention
This invention relates to fluid loading systems and more particularly to marine loading arms for transferring the fluid between an offshore terminal and a marine tanker and for returning vapor to the offshore terminal.
2. Description of the Prior Art
The production of oil and gas from offshore wells has developed into a major endeavor of the petroleum industry, and this growth has lead to the development of means for transporting petroleum products from offshore wells to shore-based refineries or storage facilities. Many of the wells are being drilled and completed in deepwater locations where the use of marine tankers of very large capacity constitutes the most practical and efficient method of transporting the petroleum products.
Some of the prior art facilities include a fluid handling means such as a fixed mooring buoy or a floating platform to which the tanker may be moored while loading. The tanker and floating platform move relative to each other during the loading operations due to wind, tides and the amount of fluid which is loaded to the tanker. The height of the tanker water line changes as the tanker is loaded or unloaded thus requiring that a flexible or articulated hose be connected between the tanker and the floating platform. When flexible hoses are used a tender is normally required to assist the tanker in picking up the flexible hoses for connection to the tanker's manifold. Such an arrangement not only requires the use of a tender but movement of the tanker may cause the flexible hoses to be broken. Also the hoses are bulky, heavy, hard to handle and require a relatively large crew of workers to connect the hose to the tanker.
Some of the other prior art loading facilities include a marine loading arm having relative complex articulated arms that are heavy, bulky, relatively expensive and require complex balancing systems because the balance of these arms changes as the fluid content of the arm changes. In addition, the transfer of large quantities of crude oil and other hydrocarbon products between the offshore facilities and the oil tanker is invariably accompanied by the generation of large volumes of vapor. At the present time these vapor are not recovered but are vented into the atmosphere where they may form explosive pockets, thereby creating a fire and safety hazard. In addition, the loss of these vapors causes shrinkage of the hydrocarbon product being transferred, which of course is quite expensive. These vapors also contaminate the air and contribute to the generation of "smog".
What is needed is petroleum transfer apparatus which is relatively easy to connect between the offshore loading facilities and a marine tanker, which provides for relative movement between the tanker and the loading facility and which recovers the vapors generated in the loading of the tanker and returns these vapors to the offshore loading facilities.